A small C WinAPI program moving the cursor in a circle

Question

So the program below will move the mouse cursor in a circle all 360 degrees for 2,5 seconds (after 2,5 seconds, the program exits and the user can use his/her cursor normally).

#include <Windows.h>
#include <math.h>

const double RADIANS_PER_DEGREE = acos(-1.0) / 180.0; // acos(-1.0) = Pi
const int SLEEP_DURATION = 2500 / 360;

int APIENTRY wWinMain(HINSTANCE hInstance,
                      HINSTANCE hPrevInstance,
                      LPWSTR    lpCmdLine,
                      int       nCmdShow)
{
    const int screenWidth  = GetSystemMetrics(SM_CXSCREEN);
    const int screenHeight = GetSystemMetrics(SM_CYSCREEN);

    const int screenCenterX = screenWidth  / 2;
    const int screenCenterY = screenHeight / 2;

    const int radius = 3 * min(screenWidth / 2, screenHeight / 2) / 4;
    int currentDegree = 90;

    for (int degree = 0; degree < 360; degree++, currentDegree++) {
        const int x = screenCenterX + (int)(radius * cos(currentDegree * RADIANS_PER_DEGREE));
        const int y = screenCenterY - (int)(radius * sin(currentDegree * RADIANS_PER_DEGREE));

        SetCursorPos(x, y);
        Sleep(SLEEP_DURATION);
    }

    return 0;
}

Critique request

I would like to hear anything that comes to mind.

Answer 1

Integer math for an integer problem

Consider a variation on Bresenham's circle algorithm for an integer only solution: faster and precise.

Note: Graphics processors use integer math for drawing circles on a screen, not floating point.

1 degree steps?

On high precision monitors, (think 2k * 2k or more) the result may look more circular (not a polygon) with finer steps. Above integer solution provides the best digitized circle.

Not standard C code

Good idea to use the systems best machine π, yet double global_variable = some_function(-1.0) is not valid. I suspect OP is not using a standard C compiler.

Alternative. Since π does not change, let the system derive the best machine π by providing code that the compiler will use even if double is many more than 64-bit.

// const double RADIANS_PER_DEGREE = acos(-1.0) / 180.0; // acos(-1.0) = Pi
const double RADIANS_PER_DEGREE = 3.1415926535897932384626433832795028841971  / 180.0;

Or define it

#ifdef M_PI // some implementation will define this, use if available.
  #define MY_PI M_PI
#else
  #define MY_PI 3.1415926535897932384626433832795028841971
#endif

const double RADIANS_PER_DEGREE = MY_PI / 180.0;

Pedantically, in rare cases, performing math like MY_PI / 180.0 will not result in the best RADIANS_PER_DEGREE and code could directly use

const double RADIANS_PER_DEGREE = 0.01745329251994329576923690768489;

Manually formatting?

Below hints that OP is not using an auto formatter. Code looks nice. Yet I would rather oblige a SW team to use auto formatting that spend time formatting.

int APIENTRY wWinMain(HINSTANCE hInstance,
                      HINSTANCE hPrevInstance,
                      LPWSTR    lpCmdLine,
                      int       nCmdShow)

Save time and increase productivity: auto-format.

Comment units

Naked code like const int SLEEP_DURATION = 2500 / 360; lacks units. How long is 2500? 2500 seconds, 2500 milliseconds? Do not lay the seeds for another big bucks units failure.

// const int SLEEP_DURATION = 2500 / 360;
const int SLEEP_DURATION = 2500 /* ms */ / 360;

Truncated quotient?

Note that 2500 / 360.0 is 6.9444... and 2500 / 360 is 6. Code may want to do things more precisely. At a minimum, consider a rounded quotient.

// const int SLEEP_DURATION = 2500 / 360;
const int SLEEP_DURATION = (2500 + 360/2) / 360;

Answer 2

continuing the item about the timer constant

const int SLEEP_DURATION = 2500 / 360;

I would do

const int RUN_TIME = 2500; // ms = 2.5 seconds
const int DEGREES_IN_CIRCLE; = 360
const int SLEEP_TIME = RUN_TIME / DEGREES_IN_CIRCLE;

and

for (int degree = 0; degree < DEGREES_IN_CIRLCE; degree++, currentDegree++)

never have magic numbers except maybe 0,1 and possibly 2 :-)

BTW +1 for const not #define